Moulds in the air, allergens on the plate
Moulds are one of the most frequently sensitised inhalant allergens, which are very difficult to escape from. During the period when their spores are at their peak, they surround us virtually everywhere we go. Moulds not only appear on the walls of buildings, but also in the air, which – especially in late summer and autumn – is full of spores invisible to the naked eye. The prevalence of mould allergy ranges from 6 to 24 per cent, with a prevalence of 44 per cent in people with atopy and up to 80 per cent in asthma sufferers [1].
What moulds have in common is that they also hide and spread rapidly in food. And this is in fact where we see them most often. In addition, there are many indications that they can cross-react with certain foods. Is there anything it is better not to eat in order to avoid the symptoms associated with a mould allergy?
Fruit, vegetables, bread… Where does mould hide?
Moulds enter the body by both inhalation and ingestion, and even through the skin and mucous membranes [2]. They very often contaminate products of plant origin, such as cereals, flour, groats, rice, bran, bread, fruit, vegetables, nuts, nuts, nuts, and cured meats. They can also be found in coffee, tea, wine, beer, milk, fruit juices [2,3]. Moulds multiply on long-stored products, e.g. root vegetables whose edible parts are in direct contact with the soil.
Dangerous mycotoxins. Beware of Moulds
The problem is that moulds are not only allergenic but also produce mycotoxins, which firstly cause spoilage of plants and secondly are harmful to health. Mycotoxins have carcinogenic ( cancerous), teratogenic (toxic to the foetus) and neurotoxic (damage to the nervous system) properties [4]. They are thermostable, meaning that they do not break down or neutralise at high temperatures. The Food and Agriculture Organisation of the United Nations (FAO) estimates that mycotoxins contaminate 25% of the world’s food crops [6].
Therefore, not only a person with an allergy to mould, but in principle none of us should eat products on which the characteristic mould bloom is visible. Even avoidance, however, does not give us a guarantee that we will not accidentally come across a product contaminated with mycotoxins. Sometimes the toxins are already in the food, but you just can’t see them at first glance because the mould hasn’t had time to develop yet.
But what if the infestation is small and only occupies a small part of the peel? It is assumed that it is not enough to cut off the mouldy part – the whole product must be discarded. This is because mycotoxins – even if the mould is only visible on the peel – may already be deep in the flesh. They migrate fastest inside soft vegetables and fruits (tomatoes, raspberries, blueberries), slowest inside hard products (carrots, apples, cheese) [5]. Mould from food can move inside the fridge, onto dishes, washing sponges, cloths, cutting boards and other kitchen utensils. And with it, dangerous bacteria often develop [6].
Forest and cultivated mushrooms
For allergy sufferers, the fact that all mushrooms show similarities in terms of protein structure seems to be particularly important. Cross-reactivity between micro-fungi and edible mushrooms – both forest and cultivated – is therefore possible. However, there are few described cases of such reactions [1]. However, it is known that symptoms can occur not only after contact with raw mushrooms, but also after eating a cooked or baked dish (pizza, lasagna) containing these ingredients [1]. Typically, these reactions are similar to OAS, Oral Allergy Syndrome.
Classic OAS is known as a symptom complex affecting people with pollen allergy who react to raw fruit and vegetables. It manifests as itching and burning of the lips, tongue and throat. In some cases, it leads to angioedema. After fungi, more serious reactions also occur in people allergic to moulds, involving not only the oral mucosa, but also the skin, gastrointestinal and respiratory systems and even the cardiovascular system (in the case of anaphylaxis) [1].
Does this mean that no fungi should be eaten if you are allergic to moulds? In allergology, it is difficult to come to a zero-sum decision. Some mould-allergic patients do react to edible mushrooms, but only in unprocessed form. However, they are not harmed by mushrooms baked on pizzas or marinated in jars [1].
It is important to remember that a cross-reaction may or may not occur. And this applies not only to edible mushrooms, but to all foods that have the potential to cross-react with moulds. The situation of each person with an allergy must therefore be considered individually, in relation to the symptoms and triggers that arise.
Mouldy cheese and matured meat
Does mould allergy also have something to do with mould cheeses? Completely different fungi are used in the production of such cheeses than those that are common inhalant allergens. So actually the answer to this question is ‘no’. And in practice, cross reactions after eating mould cheese are unlikely to occur. However, they are not excluded and the possibility of their occurrence must be taken into account. Particularly as mould fungi are allergens that still hold many secrets – their allergenic potential is still being researched. Despite the enormous diversity of species, there are certainly some common proteins [7,13].
It is known that Penicillium fungi used in the food industry can also be allergenic. And it is thanks to them (more specifically P. roqueforti – blue cheese, P. camemberti – camembert and brie, P. glaucum – gorgonzola) that mouldy cheeses acquire their characteristic aroma and aftertaste [9]. The Penicillium group also includes the fungi P. nalgiovense present in the casings of maturing sausages (fuet) [10].
Scientific papers include case reports of occupational allergy in people working in the production of maturing sausages and reports of allergic reactions in people who have eaten camembert cheese [7].
Spinach
Alternaria-spinach syndrome is another rare phenomenon that may affect people sensitive to moulds [6]. Studies have shown an association between mould allergy (Alternaria alternata, Cladosporium herbarum and/or Aspergillus fumigatus) and positive skin tests with raw spinach [7]. It is therefore likely that very similar allergens are present in these two foods. There is speculation that such reactivity may also apply to other vegetables of the Chenopodiacea (quinoa) family, of which beetroot, for example, is a representative [7].
Bee honey and jam
A non-obvious, but quite common type of food affected by mould contamination is honey. Between 2012 and 2017, samples of honey from Croatia were tested for the presence of yeasts and moulds. It turned out that the most common types of mould there were Cladosporium, Penicillium and Alternaria [11]. An analogous study was conducted in Bosnia and Herzegovina. The presence of yeasts and moulds was found in 35% of honey samples [10].
Mould can also be found in jam. If we discover even a small dot of mould under the cap, we should throw away the whole jar of jam. The runny, watery consistency favours the easy movement of mycotoxins, which can even be present near the bottom of the jar [4].
Seed sprouts
Ideal conditions for the growth of various microorganisms also exist in sprout cultures, which are a common source of exposure to bacteria, yeasts and moulds. The presence of these micro-organisms can be fatal to us because we eat sprouts mostly in their raw form and therefore with the microflora on them. There is more mould in sprouts the longer they are stored (even in the fridge) and the higher the ambient temperature in which they grow [13,14].
The same problem applies to ready-to-eat salads, in which the allergenic moulds Alternaria, Cladosporiumi Penicillium are detected [16].
Baker’s yeast
Scientific reports indicate that yeast should also be considered as a possible cross-allergen in people allergic to moulds. Anaphylactic reactions have occurred in this allergic group after eating dry yeast added to ready-made powdered sauces [14,15].
